fix(SideloadedSubtitle): guard AVSubtitlesLoader state against concurrent mutation - #127
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Efka22 wants to merge 1 commit into
Open
fix(SideloadedSubtitle): guard AVSubtitlesLoader state against concurrent mutation#127Efka22 wants to merge 1 commit into
Efka22 wants to merge 1 commit into
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Problem
Playing a stream with side-loaded text tracks intermittently crashes on iOS with
EXC_BAD_ACCESSinswift_release_dealloc.AVSubtitlesLoader.requestMap(aDictionary) andsubtitles(anArray) are mutated fromdidInterceptPlaylistRequest(type:request:)andinterceptResponse(type:url:data:)—asynccallbacks that AVFoundation invokes concurrently for the master, variant and subtitle playlists. Concurrent mutation corrupts the collections' backing storage and crashes.The unsynchronized
requestMapwas introduced in 11.0.3 (request interception for the user-agent fix); the crash has been observed in the field since.Fix
Serialize all access to each collection through a dedicated
NSLock(subtitlesLock,requestMapLock), applied via lock-guarded computed properties so no call sites change. The two collections are independent caches with no shared invariant, so they take separate locks; no code path holds both at once, so there is no lock-ordering/deadlock hazard.